Some parts of Northern Ireland could see up to 40mm of rainfall within a six hour period this weekend, according to the Met Office.
The yellow status weather warning was issued on Friday afternoon and is valid between 12:00am and 9:00am on Saturday.
"A band of rain will move west to east across Northern Ireland from the early hours of Saturday, turning heavier and more persistent in places through the morning," reads the warning.
"Many areas will see 20mm of rain in total, though a few spots could see 30 to 40 mm within around six hours.
"The rain will clear the northeast coast by mid-afternoon."